Add all the sauce and meatball ingredients to the slow cooker and gently stir to combine.
Place cover on the cooker and set to LOW for 6 hours, or HIGH for 2-3 hours.
Stovetop Method:
To a large, heavy bottomed saucepan add all the ingredients to the pot and gently stir to combine.
Bring ingredients to a boil over MED-HIGH heat, then reduce heat and simmer for 25-30 minutes or until thickened and meatballs are heated thru. Stir sauce occasionally while it simmers.
Assemble the Sliders
Preheat oven to 350 F.
Place bottom of slider rolls in 9x13 baking pan. Place one meatball and a tablespoon of sauce on each bun. Sprinkle cheese over meatballs and cover with top of bun.
Melt the butter, garlic and parmesan together either in the microwave or a small saucepan on the stove. Stir to combine. Brush butter mixture over the top of the rolls.
Cover pan with foil and bake for 20 minutes, removing foil during the last 5 minutes. They're done when the cheese is melted and sliders are heated thru. Serve with any remaining sauce.